The present invention relates to a compound semiconductor device and a method for producing the same and more particularly, it relates to a novel electrode forming technique for compound semiconductor devices such as semiconductor magnetoelectric transducers.
The magnetoelectric transducer made from a semiconductor thin film material such as a Hall element and a magnetoresistance element has been usually produced such that the sensitive portion of these elements and electrodes are formed by plating on vapor deposition of the conducting metal electrode materials forming the special pattern of the conducting electrode materials on the semiconductor thin film surface. The electrode member herein referred to implies a bonding pad for external connection of the element and the internal electrode on the sensitive portion of the element such as the shorting bar electrode of the magnetroresistance element. This type of electrode member is required to be in ohmic contact with the semiconductor thin film and is usually prepared in the form of a multi-thin layer, two or three layer structure, made of difficult conducting metals. For example, a multi-layer electrode of different conducting metals such as Ni-Cu-Au, Ge-Au, Cu-Au, Cu-Ag or the like, not only ensures the necessary ohmic contact with the semiconductor portion of the device but also ensures to prevent the electromigration of the electrode metals to the semiconductor portion prone to occur in the use of the element and to guard the semiconductor thin film in solder bonding process. A proposal to prevent the electromigration from the multi-layer electrode is disclosed in, for example, U.S. Pat. No. 4,081,601 to Donald Dinella et al, entitled "BONDING CONTACT MEMBERS TO CIRCUIT BOARDS". Such metallic materials as Ni-Cr or Cu serve an important role in providing the ohmic contact, a reinforcement, an oxidation-preventing barrir and a guard layer against the electromigration. In the conventional production of magnetoelectric transducers as mentioned above, however, the electrode formation required various sophisticated and troublesome processes including wet processes and dry processes. Especially, the conventional electrode formation process needs several times electroless plating processes which adversely affect a semiconductor thin-film device being produced so that it was inevitable to cause the migration as well as contamination due to the migration of impurities from the electrode portion to the semiconductor functional portion of the device during the production thereof. The semiconductor devices thus produced have poor reliability because of the complex production process explained above. In addition, a number of fabrication steps as required increase production cost.